A285632 Numbers k such that 6*10^k + 17 is prime.

0, 2, 4, 8, 40, 116, 234, 258, 532, 1048, 1062, 1590, 2594, 3286, 4036, 6232, 6700, 7800, 12002, 13296, 23124, 29338, 181306

Offset

1,2

Comments

For k > 1, numbers k such that the digit 6 followed by k-2 occurrences of the digit 0 followed by the digits 17 is prime (see Example section).

a(24) > 2*10^5.

If k is odd then 6*10^k + 17 is divisible by 11. - David Radcliffe, Sep 04 2018

Links

Table of n, a(n) for n=1..23.

Makoto Kamada, Factorization of near-repdigit-related numbers.

Makoto Kamada, Search for 60w17.

Example

4 is in this sequence because 6*10^4 + 17 = 60017 is prime.
Initial terms and associated primes:
a(1) = 0, 23;
a(2) = 2, 617;
a(3) = 4, 60017;
a(4) = 8, 600000017;
a(5) = 40, 60000000000000000000000000000000000000017; etc.

Mathematica

Select[Range[0, 100000], PrimeQ{6*10^# + 17] &]

Crossrefs

Cf. A056654, A268448, A269303, A270339, A270613, A270831, A270890, A270929, A271269.

Sequence in context: A058236 A259120 A319595 * A102918 A326951 A018395

Adjacent sequences: A285629 A285630 A285631 * A285633 A285634 A285635

Keyword

nonn,more,hard

Author

Robert Price, Apr 23 2017

Extensions

a(23) from Robert Price, Apr 07 2019

Status

approved